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Filename : reader.js
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module.exports = Reader

var fs = require('graceful-fs')
var Stream = require('stream').Stream
var inherits = require('inherits')
var path = require('path')
var getType = require('./get-type.js')
var hardLinks = Reader.hardLinks = {}
var Abstract = require('./abstract.js')

// Must do this *before* loading the child classes
inherits(Reader, Abstract)

var LinkReader = require('./link-reader.js')

function Reader (props, currentStat) {
  var self = this
  if (!(self instanceof Reader)) return new Reader(props, currentStat)

  if (typeof props === 'string') {
    props = { path: props }
  }

  // polymorphism.
  // call fstream.Reader(dir) to get a DirReader object, etc.
  // Note that, unlike in the Writer case, ProxyReader is going
  // to be the *normal* state of affairs, since we rarely know
  // the type of a file prior to reading it.

  var type
  var ClassType

  if (props.type && typeof props.type === 'function') {
    type = props.type
    ClassType = type
  } else {
    type = getType(props)
    ClassType = Reader
  }

  if (currentStat && !type) {
    type = getType(currentStat)
    props[type] = true
    props.type = type
  }

  switch (type) {
    case 'Directory':
      ClassType = require('./dir-reader.js')
      break

    case 'Link':
    // XXX hard links are just files.
    // However, it would be good to keep track of files' dev+inode
    // and nlink values, and create a HardLinkReader that emits
    // a linkpath value of the original copy, so that the tar
    // writer can preserve them.
    // ClassType = HardLinkReader
    // break

    case 'File':
      ClassType = require('./file-reader.js')
      break

    case 'SymbolicLink':
      ClassType = LinkReader
      break

    case 'Socket':
      ClassType = require('./socket-reader.js')
      break

    case null:
      ClassType = require('./proxy-reader.js')
      break
  }

  if (!(self instanceof ClassType)) {
    return new ClassType(props)
  }

  Abstract.call(self)

  if (!props.path) {
    self.error('Must provide a path', null, true)
  }

  self.readable = true
  self.writable = false

  self.type = type
  self.props = props
  self.depth = props.depth = props.depth || 0
  self.parent = props.parent || null
  self.root = props.root || (props.parent && props.parent.root) || self

  self._path = self.path = path.resolve(props.path)
  if (process.platform === 'win32') {
    self.path = self._path = self.path.replace(/\?/g, '_')
    if (self._path.length >= 260) {
      // how DOES one create files on the moon?
      // if the path has spaces in it, then UNC will fail.
      self._swallowErrors = true
      // if (self._path.indexOf(" ") === -1) {
      self._path = '\\\\?\\' + self.path.replace(/\//g, '\\')
    // }
    }
  }
  self.basename = props.basename = path.basename(self.path)
  self.dirname = props.dirname = path.dirname(self.path)

  // these have served their purpose, and are now just noisy clutter
  props.parent = props.root = null

  // console.error("\n\n\n%s setting size to", props.path, props.size)
  self.size = props.size
  self.filter = typeof props.filter === 'function' ? props.filter : null
  if (props.sort === 'alpha') props.sort = alphasort

  // start the ball rolling.
  // this will stat the thing, and then call self._read()
  // to start reading whatever it is.
  // console.error("calling stat", props.path, currentStat)
  self._stat(currentStat)
}

function alphasort (a, b) {
  return a === b ? 0
    : a.toLowerCase() > b.toLowerCase() ? 1
      : a.toLowerCase() < b.toLowerCase() ? -1
        : a > b ? 1
          : -1
}

Reader.prototype._stat = function (currentStat) {
  var self = this
  var props = self.props
  var stat = props.follow ? 'stat' : 'lstat'
  // console.error("Reader._stat", self._path, currentStat)
  if (currentStat) process.nextTick(statCb.bind(null, null, currentStat))
  else fs[stat](self._path, statCb)

  function statCb (er, props_) {
    // console.error("Reader._stat, statCb", self._path, props_, props_.nlink)
    if (er) return self.error(er)

    Object.keys(props_).forEach(function (k) {
      props[k] = props_[k]
    })

    // if it's not the expected size, then abort here.
    if (undefined !== self.size && props.size !== self.size) {
      return self.error('incorrect size')
    }
    self.size = props.size

    var type = getType(props)
    var handleHardlinks = props.hardlinks !== false

    // special little thing for handling hardlinks.
    if (handleHardlinks && type !== 'Directory' && props.nlink && props.nlink > 1) {
      var k = props.dev + ':' + props.ino
      // console.error("Reader has nlink", self._path, k)
      if (hardLinks[k] === self._path || !hardLinks[k]) {
        hardLinks[k] = self._path
      } else {
        // switch into hardlink mode.
        type = self.type = self.props.type = 'Link'
        self.Link = self.props.Link = true
        self.linkpath = self.props.linkpath = hardLinks[k]
        // console.error("Hardlink detected, switching mode", self._path, self.linkpath)
        // Setting __proto__ would arguably be the "correct"
        // approach here, but that just seems too wrong.
        self._stat = self._read = LinkReader.prototype._read
      }
    }

    if (self.type && self.type !== type) {
      self.error('Unexpected type: ' + type)
    }

    // if the filter doesn't pass, then just skip over this one.
    // still have to emit end so that dir-walking can move on.
    if (self.filter) {
      var who = self._proxy || self
      // special handling for ProxyReaders
      if (!self.filter.call(who, who, props)) {
        if (!self._disowned) {
          self.abort()
          self.emit('end')
          self.emit('close')
        }
        return
      }
    }

    // last chance to abort or disown before the flow starts!
    var events = ['_stat', 'stat', 'ready']
    var e = 0
    ;(function go () {
      if (self._aborted) {
        self.emit('end')
        self.emit('close')
        return
      }

      if (self._paused && self.type !== 'Directory') {
        self.once('resume', go)
        return
      }

      var ev = events[e++]
      if (!ev) {
        return self._read()
      }
      self.emit(ev, props)
      go()
    })()
  }
}

Reader.prototype.pipe = function (dest) {
  var self = this
  if (typeof dest.add === 'function') {
    // piping to a multi-compatible, and we've got directory entries.
    self.on('entry', function (entry) {
      var ret = dest.add(entry)
      if (ret === false) {
        self.pause()
      }
    })
  }

  // console.error("R Pipe apply Stream Pipe")
  return Stream.prototype.pipe.apply(this, arguments)
}

Reader.prototype.pause = function (who) {
  this._paused = true
  who = who || this
  this.emit('pause', who)
  if (this._stream) this._stream.pause(who)
}

Reader.prototype.resume = function (who) {
  this._paused = false
  who = who || this
  this.emit('resume', who)
  if (this._stream) this._stream.resume(who)
  this._read()
}

Reader.prototype._read = function () {
  this.error('Cannot read unknown type: ' + this.type)
}